The present disclosure relates to a zoom lens suitable for a small digital video camera or a digital still camera which may have a zoom factor of, for example, about 10 to 15 magnifications, and to an image pickup unit using such a zoom lens. In particular, the disclosure relates to a zoom lens having an optical image-blur compensation function and an image pickup unit using the zoom lens.
Recently, small-size image pickup units such as digital video camera and a digital camera have been widely used as a home unit. Such small-size image pickup units are typically demanded to be reduced in size in great consideration of portability, be improved in image quality, and be increased in magnification. Photographing lenses to be mounted in such image pickup units, particularly a zoom lens, are therefore also demanded to be reduced in size through a reduction in overall length and depth, and be improved in lens performance. Furthermore, the zoom lens is recently greatly demanded to have in particular an optical image-blur compensation function. Consequently, a difficulty level of design to satisfy such demands, such as small size, high image quality, high magnification, and the optical image-blur compensation function, is now extremely high. Under such circumstances, for example, Japanese Unexamined Patent Application Publication Nos. 2003-228001, 2006-23593, and 2003-241098 (JP-A-2003-228001, JP-A-2006-23593, and J-PA-2003-241098) each disclose a zoom lens having five or more lens groups, in which an optical image-blur compensation technique is introduced.
The zoom lens described in JP-A-2003-228001 is configured of, in order from an object plane, a first lens group having a positive refracting power, a second lens group having a negative refracting power, a third lens group having a positive refracting power, a fourth lens group having a negative refracting power, and a fifth lens group having a positive refracting power. In this zoom lens, the third lens group includes a lens having a positive refracting power and a lens having a negative refracting power, and is configured to be movable in a direction perpendicular to a light axis in order to compensate a variation in an image due to shake of hands. A zoom lens for a video camera, which has optical image-blur compensation capability, is achieved through such a configuration.
The zoom lens described in JP-A-2006-23593 is configured of, in order from an object plane, a first lens group having a positive refracting power, a second lens group having a negative refracting power, a third lens group having a positive refracting power, a fourth lens group having a positive refracting power, and a fifth lens group having a positive refracting power. In this zoom lens, the fifth lens group is configured of a positive sub-group having a positive refracting power and a negative sub-group having a negative refracting power, and the positive sub-group is shifted in a direction substantially perpendicular to a light axis direction to shift an image. A zoom lens, which has optical image-blur compensation capability, for use in a video camera, etc., is achieved through such a configuration.
The zoom lens described in JP-A-2003-241098 includes a varying-power optical system having a vibration-proof function, in which lens groups other than a first lens group nearest to an object are provided as vibration-proof lens groups. In the zoom lens, the vibration-proof lens group includes, in order from an object plane, a front section, a middle section, and a rear section, and the front section and the rear section are moved in a direction substantially perpendicular to a light axis to compensate blur of an image.